Ground
A ground is a fundamental part of a properly equipped station. Without a ground, you are at risk of damaging your equipment or worse, causing physical harm to people around the device as a radio station changes the way your inhouse electric circuit behaves in case of a lightning strike.
Different types of grounds
The ARRL distinguishes between three different types of grounds:
- Satefy ground - to protect against defects in your transceiver that may leak energy even though it's power plug is grounded
- Lightning ground - to protect against lightning strikes on the antenna or the electricity supply
- RF ground - to properly install special antennas that require a ground
Here we will consider a station ground as covering both the needs of a safety and lightning ground. A safety ground (the outside of your transceiver, for example) can be connected to the electric supply ground of your house, but to keep things safe and avoid confusion, we will not connect your station ground to the electric supply.
Also note that lightning protection can be done through the installation of surge protectors, but it is still important to connect your station to a separate safety ground.
What a ground is not
A ground is not the regular electric supply ground: you need a separate ground that is not connected to your electric supply ground.
You should not use a station ground as an RF ground (but you can use an RF ground as a station ground). Those are two different things for two different purposes.
Building a proper ground
A proper station ground will be a copper strip that runs through your station's rigs and serves as a tie point for the ground leads of all radio equipment within your shack. That station ground is then connected to a non-electric supply ground. Such a ground may be a metallic cold water pipe (not plastic, not hot water!) or better yet, a custom-made ground rod, connected through a gage 6 or smaller (gage, not size).
Cold water pipes
Cold water pipes can act as a ground rod, as long as the house power supply isn't also connected there. (Hint: talk to your electrician if it's so, that's not supposed to happen.)
Ground rods
A ground rod is made of copper-clad or plain copper steel. It should generally be driven into the soil at least 10 feet (3.25m).
Ground plates
A ground plate is also a valid ground. It's a plate of copper-clad steel or plain copper made of a 30cm per 30cm square, buried 45cm below the soil.
Connecting to the ground
As mentioned above, the station ground itself is a braided, 14-gage copper strip that runs within the shack. You can use the braid from spare RG-8/U coax if you have extra.
The station ground needs to be connected directly to the ground built above, and that connexion must be as short as possible. If the ground is a quarter of the wavelength or an odd number multiple of the quarter wavelength, it will start emitting RF energy and can cause severe burn.
It is therefore a challenge to connect your ground properly for anybody building a station on the second floor or similar higher ground.
External links
- Good article about problems a ground protects from
- Canadian Amateur Radio Basic Qualification Study Guide - source for some of the specifications for the ground here
- Grounding Systems for Amateur Radio Stations - The Tech Bench Elmers Amateur Radio Society (KF6GDJ)
- ARRL grounding Q&A
- Excellent serie from the ARRL on how to completely ground a station safely
- Controversial article trying to tone down the usual warnings about grounding